Relationship between Dining Place, Iodine Source, and Iodine Nutrition in School-Age Children: A Cross-Sectional Study in China

Objective This study assesses the impact of iodine-rich processed foods and dining places on the iodine nutritional status of children.Methods School-aged children (SAC) in seven provinces in China were selected by school-based multi-stage sampling. Urinary iodine, salt iodine, and thyroid volume (TVOL) were determined. Questionnaires were used to investigate dining places and iodine-rich processed foods. The water iodine was from the 2017 national survey. Multi-factor regression analysis was used to find correlations between variables.Results Children ate 78.7% of their meals at home, 15.1% at school canteens, and 6.1% at other places. The percentage of daily iodine intake from water, iodized salt, iodine-rich processed foods, and cooked food were 1.0%, 79.2%, 1.5%, and 18.4%, respectively. The salt iodine was correlated with the urinary iodine and TVOL, respectively (r = 0.999 and -0.997, P < 0.05). The iodine intake in processed foods was weakly correlated with the TVOL (r = 0.080, P < 0.01). Non-iodized salt used in processed foods or diets when eating out had less effect on children's iodine nutrition status.Conclusion Iodized salt remains the primary source of daily iodine intake of SAC, and processed food has less effect on iodine nutrition. Therefore, for children, iodized salt should be a compulsory supplement in their routine diet.